fix: Fix Xaml merge task not supproting conditional namespaces

src/SourceGenerators/Uno.UI.Tasks/BatchMergeXaml/MergedDictionary.cs

@@ -108,6 +108,9 @@ private MergedDictionary(XmlDocument document, MergedDictionary parentDictionary
             mergedThemeDictionaryByKeyDictionary = new Dictionary<string, MergedDictionary>();
             namespaceList = new List<string>();
             this.parentDictionary = parentDictionary;
+
+            AddNamespace("mc", "http://schemas.openxmlformats.org/markup-compatibility/2006");
+            xmlElement.SetAttribute("Ignorable", "http://schemas.openxmlformats.org/markup-compatibility/2006", "ios android wasm skia");
         }
 
         private void AddNamespace(string xmlnsString, string namespaceString)

src/Uno.UI.FluentTheme/themeresources.xaml

@@ -1,6 +1,6 @@
-<ResourceDictionary xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:media="using:Microsoft.UI.Xaml.Media" xmlns:controls="using:Microsoft.UI.Xaml.Controls" xmlns:primitives="using:Microsoft.UI.Xaml.Controls.Primitives" xmlns:wasm="http://uno.ui/wasm" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" xmlns:uno="using:Uno.UI.Xaml.Controls" xmlns:automation="clr-namespace:Windows.UI.Xaml.Automation" xmlns:not_mux="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:contract4Present="http://schemas.microsoft.com/winfx/2006/xaml/presentation?IsApiContractPresent(Windows.Foundation.UniversalApiContract,4)" xmlns:contract7Present="http://schemas.microsoft.com/winfx/2006/xaml/presentation?IsApiContractPresent(Windows.Foundation.UniversalApiContract,7)" xmlns:contract7NotPresent="http://schemas.microsoft.com/winfx/2006/xaml/presentation?IsApiContractNotPresent(Windows.Foundation.UniversalApiContract,7)" xmlns:primitiveContract7Present="using:Microsoft.UI.Xaml.Controls.Primitives?IsApiContractPresent(Windows.Foundation.UniversalApiContract,7)" xmlns:contract4NotPresent="http://schemas.microsoft.com/winfx/2006/xaml/presentation?IsApiContractNotPresent(Windows.Foundation.UniversalApiContract,4)" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:unouwp="http://schemas.microsoft.com/winfx/2006/xaml/presentation?IsApiContractNotPresent(Uno.WinUI,1)" xmlns:win="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:contract6Present="http://schemas.microsoft.com/winfx/2006/xaml/presentation?IsApiContractPresent(Windows.Foundation.UniversalApiContract,6)" xmlns:ios="http://platform.uno/ios" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
+<ResourceDictionary xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="ios android wasm skia" xmlns:media="using:Microsoft.UI.Xaml.Media" xmlns:controls="using:Microsoft.UI.Xaml.Controls" xmlns:primitives="using:Microsoft.UI.Xaml.Controls.Primitives" xmlns:wasm="http://uno.ui/wasm" xmlns:uno="using:Uno.UI.Xaml.Controls" xmlns:automation="clr-namespace:Windows.UI.Xaml.Automation" xmlns:not_mux="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:contract4Present="http://schemas.microsoft.com/winfx/2006/xaml/presentation?IsApiContractPresent(Windows.Foundation.UniversalApiContract,4)" xmlns:contract7Present="http://schemas.microsoft.com/winfx/2006/xaml/presentation?IsApiContractPresent(Windows.Foundation.UniversalApiContract,7)" xmlns:contract7NotPresent="http://schemas.microsoft.com/winfx/2006/xaml/presentation?IsApiContractNotPresent(Windows.Foundation.UniversalApiContract,7)" xmlns:primitiveContract7Present="using:Microsoft.UI.Xaml.Controls.Primitives?IsApiContractPresent(Windows.Foundation.UniversalApiContract,7)" xmlns:contract4NotPresent="http://schemas.microsoft.com/winfx/2006/xaml/presentation?IsApiContractNotPresent(Windows.Foundation.UniversalApiContract,4)" xmlns:d="http://schemas.microsoft.com/expression/blend/2008" xmlns:unouwp="http://schemas.microsoft.com/winfx/2006/xaml/presentation?IsApiContractNotPresent(Uno.WinUI,1)" xmlns:win="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:contract6Present="http://schemas.microsoft.com/winfx/2006/xaml/presentation?IsApiContractPresent(Windows.Foundation.UniversalApiContract,6)" xmlns:ios="http://platform.uno/ios" xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation">
   <ResourceDictionary.ThemeDictionaries>
-    <ResourceDictionary x:Key="Default">
+    <ResourceDictionary xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="ios android wasm skia" x:Key="Default">
       <SolidColorBrush x:Key="SystemControlTransparentBrush" Color="Transparent" />
       <x:Boolean x:Key="UseSystemFocusVisuals">True</x:Boolean>
       <Thickness x:Key="TextControlBorderThemeThickness">1</Thickness>
@@ -1481,7 +1481,7 @@
       <Thickness x:Key="TreeViewItemBorderThemeThickness">1</Thickness>
       <x:Double x:Key="TreeViewItemMinHeight">32</x:Double>
     </ResourceDictionary>
-    <ResourceDictionary x:Key="Light">
+    <ResourceDictionary xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="ios android wasm skia" x:Key="Light">
       <SolidColorBrush x:Key="SystemControlTransparentBrush" Color="Transparent" />
       <x:Boolean x:Key="UseSystemFocusVisuals">True</x:Boolean>
       <Thickness x:Key="TextControlBorderThemeThickness">1</Thickness>
@@ -2962,7 +2962,7 @@
       <Thickness x:Key="TreeViewItemBorderThemeThickness">1</Thickness>
       <x:Double x:Key="TreeViewItemMinHeight">32</x:Double>
     </ResourceDictionary>
-    <ResourceDictionary x:Key="HighContrast">
+    <ResourceDictionary xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" mc:Ignorable="ios android wasm skia" x:Key="HighContrast">
       <SolidColorBrush x:Key="SystemControlTransparentBrush" Color="Transparent" />
       <x:Boolean x:Key="UseSystemFocusVisuals">True</x:Boolean>
       <Thickness x:Key="TextControlBorderThemeThickness">1</Thickness>